In a startup, you usually don't have the time or resources to play with tech and learn cool new things. Instead, you're hastily producing another simplest thing that could possibly work, using predictable tools you already know in and out. You're lucky if it's RoR or Node; you could be stuck with Go or PHP.

In an early-stage startup you work long hours, and are preoccupied with two things: how to divinate what the users actually want (usually nebulous and contradictory), and how to quickly make it work this way. You can easily lose track of what's interesting in the broader landscape, instead of enjoying new hotness as it gets released.

If you want some leisure, join a large established company, work efficiently, and you'll have plenty of paid time to fiddle with the cool stuff developed inside it, and elsewhere. Or become so advanced that a large company will task you with solving something actually novel, not amenable to off-the-shelf solutions.